The present invention relates to a flat panel display device, and in particular to a field emission display (hereinafter FED), a flat panel display device incorporating in a hermetic container an electron source comprising a large number of cold cathode elements arranged in a matrix configuration for emitting electrons.
Known as electron emitting elements for use in FED are surface conduction type emission element (hereinafter SED type), field emission type (hereinafter FE type) and metal-insulator-metal type emission element (hereinafter MIM type). Among the FE type, there are the Spindt type made up chiefly of a metal such as Mo and a semiconductor material such as Si and the CNT (Carbon Nanotube) type using carbon nanotubes as its electron source. The SED type is disclosed in Japanese Patent Application Laid-Open No. 2000-164129, for example, and the MIM type is disclosed in Japanese Patent Application Laid-Open Nos. 2001-101965 and 2001-243901, for example.
As shown in FIG. 21 of Japanese Patent Application Laid-Open No. 2001-101965, for example, the FED type comprises: a rear substrate made of an insulating material and provided with an electron source composed of cold cathode elements serving as electron emission elements, arranged in a matrix configuration; and a display substrate made of a light-transmissive material, disposed to face the rear substrate, and provided with phosphors for emitting three primary colors of light, R, G, B when struck by electrons from the electron source. A peripheral frame is sandwiched between the rear and display substrates, and the rear and display substrates and the peripheral frame are sealed together as by a frit glass to complete a hermetic envelope, and then its interior is evacuated to a pressure in a range of from 10−5 to 10−7 torr.
In the FED, support members (hereinafter spacers) are provided between the rear and display substrates to prevent breakage of the hermetic envelope due to atmospheric pressure. Careful consideration is given to locations of the spacers so that they do not interfere with trajectories of electrons traveling from the electron emission elements toward the phosphors. Spacers can be located on a black matrix in the form of stripes disposed between the R, G and B phosphors, for example. An example of the arrangement of R, G and B phosphors and a black matrix is disclosed in Japanese Patent Application Laid-Open No. 2000-306510, for example.
Spacers for use in the FED are disclosed in SID 97 Digest (1997 Society for Information Display International Symposium Digest of Technical Papers Vol. 28, (1997)), pp. 52–55, for example. The flat panel display device reported in this paper has a 10-inch diagonal screen provided with 240×240×3 color-pixels (one pixel comprises a triad of R, G and B color-pixels), and is configured such that 28 spacers of 40×3×0.2 mm3 are arranged. A spacing between the rear and display substrates is 3 mm, and a thickness and an aspect ratio of the spacers are 0.2 mm and 15, respectively. Vertical and horizontal pitches of color-pixels are 0.65 mm and 0.29 mm, respectively. The width of the spacers is greater compared with the pitches of the color-pixels even now. Japanese Patent Application Laid-Open No. 2000-294170 by one of the present inventors and others discloses a technique which provides the rear and display substrates with recesses conforming to the shape of spacers, and fits the spacers in the recesses, for the purpose of facilitating of attachment of the spacers.